It was a very clear and intuitive explanation as well. I was most intrigued by their optical system used to encode and decode light structures in space and time. Though, I didn't quite understand their discussion of 4D holograms at the end, they seem to imply that we can now achieve actual 3D holograms of images using time-reversed light waves and also have these holograms move over time?

Edit: the author has a longer video with timestamps[0] as well, perhaps the details and implications are discussed there.

[0] https://www.youtube.com/watch?v=9hVEJvfWjRQ